What is it?
Feline hepatic lipidosis (FHL), also known as fatty liver disease in cats, is characterized by an unusual build-up of a type of fat called triacylglycerol (TAG) in more than 80% of liver cells and an increase of liver weight by 50%. This is a common liver disease in cats, and FHL can develop in any situation when there is no food intake (anorexia), or when food intake is reduced (hyporexia). Usually, FHL initiates when food (energy) intake is reduced by 50-75% Basically, the fatty liver is overwhelmed by an influx of fatty acids and can’t process them fast enough, so it stores them instead. Obese cats are particularly susceptible to developing FHL when they are not eating (anorexia) or eating only little bits (hyporexia) because of the amount of fatty acids that can be mobilized from body fat, and because they are prone to insulin resistance. Also, deficiency of certain nutrients, such as protein, the sulfur amino acids methionine and cysteine, B-vitamins like choline, cobalamin, folate and pyridoxin and omega-3 fatty acids plays a role in this disease. It can also occur in conjunction with other diseases, such as diabetes mellitus, pancreatitis or hepatitis, as well as stresses such as a sudden diet change, transition of household, or introduction to new people or animals. In summary, any disease or situation that reduces the cat´s appetite can lead to FHL. Even an accelerated weight loss program could cause FHL if the cat is not properly monitored.
Clinical Signs to Watch For
Clinical signs related to FHL are not specific and include rapid weight loss, dehydration, lethargy, vomiting, weakness, diarrhea, a pale appearance to the gums or jaundice, which causes a yellow color in the skin and eyes (Center, 2005).
Veterinary Examination
If your veterinarian is suspicious your cat may have FHL, bloodwork is one of the diagnostics that will help confirm their suspicions. Elevated liver enzymes are usually the result of fat accumulation in the liver. Research has shown that cats with FHL show many abnormalities as higher blood cortisol, glucose, lactate, glucagon, growth hormone, catecholamines, and non-esterified fatty acids, while simultaneously experiencing low insulin levels. A radiograph or ultrasound of the liver may also be performed, to see if the organ is enlarged, as well as a liver biopsy to confirm diagnosis. However, the risk for biopsies may limit the diagnosis of FHL, which is often based on the history, physical exam, bloodwork and quick weight loss.
In Humans
Feline hepatic lipidosis shares many similarities with non-alcoholic fatty liver disease (NAFLD), seen in humans. NAFLD is a progressive disease that also starts with food deprivation, resulting in fat accumulation in the liver. Left untreated, it can cause scar tissue in the liver, known as cirrhosis, which in turn hinders the liver’s normal function and can potentially cause liver failure. These conditions associated with NAFLD are closely associated with diabetes as fatty liver is accompanied by insulin resistance (Reddy & Rao, 2006). In this state, whole body fat mobilization and fat deposition in the liver are increased, therefore allowing fatty acids to accumulate in the liver (Reddy & Rao, 2006).
How is it Treated?
Your pet will require hospitalisation with IV fluids, electrolytes and medications. Aside from medical management to support liver function and overall supportive care of the patient, treatment of the disease focuses on nutritional support. As cats with FHL are not eating enough on their own, advanced nutrition intervention is usually needed. A feeding tube is often placed in the nose or in the oesophagus to ensure feeding of a high protein, high energy liquid veterinary therapeutic diet to ensure essential nutrient and energy intake, avoid deficiencies and therefore prevent additional fat mobilization from the body. Once they are ready to go home, cats often leave the hospital with a feeding tube to ensure proper nutrition at home. Your veterinarian will teach you about the care and use of this tube, which will remain in place until your pet’s appetite returns. This treatment usually takes 6-7 weeks before removal of the feeding tube (Center, 2005). Additional veterinary care may be needed to diagnose and treat the medical reason for the initial loss of appetite.
Feline Hepatic Lipidosis is a medical emergency. If you suspect your cat may be suffering from FHL, demonstrating some of the above symptoms, has a reduced food intake, or involuntary starvation, contact your veterinarian immediately.
Prevention
The best prevention for FHL is maintaining a healthy body weight and body condition for your cat, as determined by their veterinarian. This reduces the risks associated with fat accumulation, and helps to ensure proper metabolism, leading to a longer and healthier life for your cat. Always make sure to consult with your veterinarian about the best treatment and prevention plans for your cat.
If your cat is undergoing a weight loss program, it is critical to monitor the body weight and have the support of your veterinarian to prevent weight loss that is too fast and could lead to FHL. A gradual transition to any new diet is also important to reduce the risk of food rejection and FHL, as well as preventing any condition or situations that can affect your cat’s ability to eat or have access to food.
FHL can be reversed and prevented by nutritional therapy due to the underlying interaction with reduced/lack of food intake and metabolism; a strategy that can pose a convenient solution for veterinarians when creating treatment plans. Current studies at the OVC are investigating the potential link between choline supplementation and fat metabolism in cats, with some previously published studies listed below. It will be exciting to see the end results of these studies and the health implications for both cats and humans with fatty liver disease: stay tuned!
Published studies from our lab related to choline:
https://doi.org/10.1093/jas/skac202″ HYPERLINK “https://doi.org/10.1093/jas/skac202” Rankovic, A., et al. (2022). Dose-response relationship between dietary choline and serum lipid profile, energy expenditure and respiratory quotient in overweight adult cats fed at maintenance energy requirements. Journal of Animal Science, 100 (7):skac202.
Written by:
Jessica Fletcher, BScAgr, MSc Student
Reviewed by:
Dr. Erico de Mello Ribeiro, MV, MSc, PhD, DVSc Candidate, ECVCN Resident
Dr. Adronie Verbrugghe DVM, PhD, Dip ECVCN
References:
Armstrong PJ, Blanchard G. (2009). Hepatic lipidosis in cats. The Veterinary Clinics of North America: Small Animal Practice; 39(3):599–616.
Biourge VC, Massat B, Groff JM, et al. (1994). Effects of protein, lipid, or carbohydrate supplementation on hepatic lipid accumulation during rapid weight loss in obese cats. American Journal of Veterinary Research; 55(10):1406–15.
Blanchard, G, Paragon, BM, Serougne, C, Ferezou, J, Milliat, F, Lutton, C. (2004). Plasma lipids, lipoprotein composition and profile during induction and treatment of hepatic lipidosis in cats and the metabolic effect of one daily meal in healthy cats. Journal of Animal Physiology and Animal Nutrition. 88: 73–87.
Brown, B, Mauldin, GE, Armstrong, J, Moroff, SD, & Mauldin, GN. (2000). Metabolic and hormonal alterations in cats with hepatic lipidosis. Journal of veterinary internal medicine. 14(1), 20–26.
Center, SA, Crawford, MA, Guida, L, et al. (1993). A retrospective study of 77 cats with severe hepatic lipidosis: 1975-1990. Journal of Veterinary Internal Medicine. 7(6):349–59.
Center, SA. Feline hepatic lipidosis. (2005). Veterinary Clinics of North America: Small Animal Practice; 35(1):225–69.
Okada, Y, Kobayashi, M, Sawamura, M, & Arai, T. (2017). Comparison of Visceral Fat Accumulation and Metabolome Markers among Cats of Varying BCS and Novel Classification of Feline Obesity and Metabolic Syndrome. Frontiers in Veterinary Science, 4, 17.
Reddy, JK, & Rao, MS. (2006). Lipid metabolism and liver inflammation. II. Fatty liver disease and fatty acid oxidation. American journal of physiology. Gastrointestinal and liver physiology, 290(5), G852–G858.
Valtolina, C, & Favier, RP. (2017). Feline Hepatic Lipidosis. The Veterinary clinics of North America. Small animal practice, 47(3), 683–702.
Verbrugghe, A., & Bakovic, M. (2013). Peculiarities of one-carbon metabolism in the strict carnivorous cat and the role in feline hepatic lipidosis. Nutrients, 5(7), 2811–2835.